It seems like you were able to do what I have been trying to figure out for days now. I assume you have a Family Share plan where you share your minutes and text but have independent data plans?
Can you kindly explain how you went about making this work please? I believe we have very similar situations except I have the Family Share plan with one current unlimited data smartphone and one basic phone with no data at all but it does have an upgrade available. Where I think I may run into trouble is adding data service to the basic line once I use the upgrade to get a new phone (Note 2) because I feel like the only way to add data is to switch to the new Share Everything plans.
I can try to explain
My wife and I have a family plan with shared minutes and texts, but we each have our own unlimited data plans. I wanted to get a new phone at the discounted price but I wasnt about to give up unlimited data. I bought a cheap dumb phone on Craigslist. I then went and bought a new iPhone and added a new line to our plan, sharing the minutes and texts with our current plan and adding a data package, I think it was 2GB. I then went home and tried to switch the iPhone to my line and activate the dumb phone. Verizon told me the iPhone had to be de-activated for 24 hours before they could "unlock" the sim and swap the phone to my line.
I waited more than 24 hours since I was going out of town for the weekend, I think it was 3 days. I called back, switched the iPhone to my line, activated the dumb phone on the new line. Now I have the new phone, purchased at the discounted price, kept both unlimited data plans and now I have a 3rd line for $10 a month. I only got charged the $30 activation fee for adding the new line and I paid for 3-4 days of data on that new line.
Hope I explained it good enough!